How do I stop myself from being so irritable and angry with being bipolar?

It sounds like you are aware of when it is starting to happen. Commit to yourself and be very mindful of those signs. Commit to being quiet and doing something that you know will draw that feeling away. Tell your mom and anyone else that you want, when you start to see the signs, that you are going to just be quiet and not talk until it passes. That way they will understand your silence is not a negative towards them. I have used that method with good results. Being quiet is good because when you get angry, some things seem like a really good idea, then later you have to deal with something else entirely.